BIODEGRADABLE POLYURETHANE FOAMS DERIVED FROM MOLASSES

Abstract

Rigid polyurethane(PU) foams containing molasses were prepared according to the following procedure. The molasses-polyol(MP), which is a solution of molasses in polyethylene glycol(PEG) having a molecular weight of 200, was mixed with commercial polyols such as polypropylene glycol(PPG) and sucrose based polyol. The obtained mixture was reacted with diphenylmethane diisocyanate(MDI) after the addition of silicone surfactant, catalyst and blowing agent under vigorous stirring at room temperature. During the reaction, the cream time and the rise time of PU foams were measured. The cream time and the rise time of PU foams decreased with increasing MP contents due to the influence of primary alcohol in PEG. Thermal and mechanical properties of PU foams were studied by thermogravimetry, differential scanning calorimetry and compression tests. The thermal decomposition temperatures of PU's containing sucrose based polyols decreased slightly with increasing MP content in the polyols. These results suggest that relatively thermally unstable saccharide components in PU molecular chains reduce the thermal stability of PU's. The glass transition temperatures, the compressive strength and elasticity of PU's containing sucrose based polyols decreased with increasing MP contents, and those of PU's containing PPG increased with increasing MP contents in PU's. This suggests that sucrose in molasses and sucrose based polyols act as hard segments in PU molecules. Biodegradability of PU foams was studied by a soil burial method. The PU foams derived from molasses had higher degradability than that of PU foams without molasses.